Philadelphia Eagles Sullivan signed with the
Philadelphia Eagles as an
undrafted free agent on April 28, 2018. He failed to make the Eagles' 53-man roster out of training camp, but was subsequently signed to the team's
practice squad on September 2. Sullivan was promoted to the active roster on October 25, 2018, after
defensive end Derek Barnett was placed on
injured reserve. Sullivan made his NFL debut on October 28, 2018, against the
Jacksonville Jaguars, playing on special teams. Sullivan made his first career start on November 25, 2018, against the
New York Giants, he made three tackles and deflected a pass before leaving the game due to injury. He was waived by the Eagles on December 24, 2018, and re-signed to the practice squad for the rest of the season and signed a reserve/future contract with the Eagles on January 14, 2019. In his rookie season, Sullivan played in five games (one start) and made seven tackles. He was waived on May 1, 2019.
Green Bay Packers On May 6, 2019, Sullivan signed with the
Green Bay Packers and made the team out of training camp. In week 5 against the
Dallas Cowboys, Sullivan intercepted a pass from
Dak Prescott in the 34–24 win. Sullivan played in all 16 of the Packers' regular season games and recorded 30 tackles with six passes defended, one interception, and one forced fumble while also playing in both of the team's playoff games with one start. On March 17, 2020, the Packers tendered Sullivan for one year as an exclusive rights free agent. He signed the tender on April 27, 2020. On September 20, 2020, against the
Detroit Lions Sullivan intercepted a pass thrown by
Matthew Stafford on the Lions' seven-yard line and returned it for his first career touchdown during the 42–21 win. The Packers placed a
restricted free agent tender on Sullivan on March 17, 2021. He signed the one-year contract on April 23.
Minnesota Vikings On March 25, 2022, Sullivan signed a one-year contract with the
Minnesota Vikings. In the historic comeback win after trailing the Indianapolis Colts 33–0, Sullivan incurred a costly fifteen-yard penalty for unsportsmanlike conduct for tossing his helmet after learning in the endzone that his fumble recovery had not been ruled a fumble at all. In the first half, Sullivan had stripped a Colt of the football and taken it across the goal line but that play was ruled as not a fumble.
Pittsburgh Steelers On May 2, 2023, Sullivan signed with the
Pittsburgh Steelers. ==NFL career statistics==